Heating coil for cracking hydrocarbon oils



Oct. 4, 1932. J. 'c, BLACK HEATING COIL FOR CRACKING HYDOCARBON OILS .Original Filed Nov. 6, 1922 n /r A .mi

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.5W ATTORN Patented Oct. 4, 1932 UNITED STATES PATENT ol-FTCEl JOHN C. BLACK, OF- LOS ANGELES, CALIFORNIA, ASSIGrNOR, BY MESNE ASSIGNMENTS,

TO GASOLINE PRODUCTS COMPANY, INC., OF WILMINGTON, DELAWARE, A CORPO- RATION 0F DELAWARE HEATING COIL FOR CRACKING HYDROCARBON OILS Griginal application led November 6, 1922, Serial No. 599,403. Divided and this application led September 14, 1927.

This application is a division of the pending application of John C. Black, Serial Number 599,403, led November 6, 1922, for heating coil for cracking hydrocarbons.

This invention relates to the art of vproducing low boiling point hydrocarbons from those of high boiling point hydrocarbons and more particularly by the process described in my Patent 1,426,813, in which the hydrocarbons are heated in a coil and maintained while being heated at a pressure suiicient to prevent vaporization of the hydrocarbons.

In the before mentioned patent, I describe a process wherein I employ temperatures as high as 1000o F. and pressures as high as 1000 pounds or more per square inch. To withstand these excessive temperatures and pressures, it is essential to construct the heating elements or coils in a very substantial and safe manner, and furthermore, it is advantageous to so construct the coil that each pipe or tube can be easily opened for inspection and cleaning without dismantling it. It is also advantageous to be able to construct the coils outside of the furnace =and insert them 1n the furnace as a complete coil only requiring connection to the balance of the appa- Aratus to make it operative.

I have discovered that the presence of sulphur in the hydrocarbons, either as free sulphur or as sulphur compounds, will readily attack the steel of the tubes when the coil is in operation under the high pressure and high heat employed in the process. To overcome this difficulty, I prefer to use an alloy steel such as nickel steel or chrome nickel steel, or I may use a tube which has been heat-treated with aluminum wherein a thin coating of aluminum iron or aluminum steel alloy is produced which acts as a protective surface to the tube and prevents to a great extent the destructive action of the sulphur or sulphur compounds.

To withstand the high pressure employed in the process and especially so under thel high heat employed, I prefer to use a seamless drawn tube in preference to a pipe made by welding, such as the ordinary butt or lapwelded pipe of commerce, as I have found that such pipe will not stand the strains as Serial No. 219,538.

well as the seamless tubing. However, I do not Wish to limit myself in the construction of my coils, as either seamless or welded seam pipe may be employed.

Referring to the drawing: Figure 1 is a sectional elevation of the coil placed in the furnace.

drawing, 1 is shown as a furnace with three compartments, one for combustion space, one for the main coil 2 and one for the economizer coil 3. The furnace is litted with a stack 4 to carry off the products of combustion; 5 is an oil or gas burner of the ordinary type; 6 is a door to afford access to the coil 2; 7 are the .blocks which form the crossovers from tube to tube and 8 are clamps to hold the coil together; 9 are angle blocks for making connections one part with the' other; 10 are plugs .l in the angle blocks and coil blocks to afford means for inspection and cleaning the tubes; 11 is a connecting tube from the outlet of the coil to the digester or carbon catcher described in my Patent 1,426,813; 12 are the tubes shown in Figures 2 and 4; 13 the threaded connection of the tube and block; 14, 15

and 16 are the three sections that go to make up the clamp 8 shown in Figure 3.

It will be noted in Figure 1 that the coil 2 is located entirely within the heating zone of the furnace with only the ingress and egress connections out of the heating zone-this I have found desirable and in some cases necessary to prevent the corrosive action of the sulphur or sulphur compounds in the hydrocarbons being cracked, as I have found by experience that there is a thin coating of carbon deposited upon the inside of the tubes which acts as a protective coating thereon and the sulphur present inthe hydrocarbons will not attack the steel either in the tubes or the return connectors. This protective carbon or carbonaceous deposit is only formed in the tubes or return connectors when they are inside the heating zone of the furnace and is due, I believe, to the baking action of thehigh heat found in the heating zone and to which the coil is subjected. This is a very important feature of my cracking coil, as it adds very materially to the life of the coil. It also has the added feature of the entire coil acting as a heat absorbing element, no portion of which is outside the heating zone.

The coil as constructed consists of a plural ity of tubes arranged in layers each tube in one layer being connected to a tube in another layer by means of steel blocks bored through in line with the tubes, one side being counterbored and threaded to receive the threaded end of the tube and the other end of the bored hole is threaded to receive removable threaded plugs which act as closures when the coil is in operation, or when removed will afford f means for inspecting and cleaning the ytubes.

Lengthwise with the blocks is a bore hole, preferably the size of the inside diameter of the tubes, and in communication with the two previously/ described bore holes, the axis of the longitudinal bore hole intersects the axes of the two transverse bore holes; the up er end of the longitudinal bore hole is threa ed to receive a threaded plug which has the same flllnction as the two previously described p u s.'

Tghe longitudinal bore hole is not bored beyond the point where it makes full communication with the second tube opening, although it could be drilled through and threaded the same as the other end, but nothing would be gained by this and expense` wouldbe incurred.

In place of threading or screwing the tubes into the blocks, they may be Welded in, the

blocks then being only counterbored to receive the tubes and not threaded.

To hold the coils as a unit, I employ a three piece cast iron or steel clamp, usually three in number to each coil, one near each end and one in the middle; the middle portion of the clamp is grooved out with semi-circular grooves to receive the tubing and so spaced as to give the proper spacing of the tubes; the upper and lower portions of the clamp are also grooved out in .a similar manner to the middle portion and .have extended ends through which pass bolts to fasten the top, bottom and middle sections together, thus securely fastening the various tubes into a single rigid unit.

I prefer to construct the coil in a symmetrical manner as to spacing of the tubes, that to say any lower tube is equidistant from the two tubes immediately abovel it, and vice versa, any upper tube is equidistant from the two tubes immediately below it.

in the reverse direction. By this expedient,

tubes placed parallel with the longitudinal .axis of the coil will connect opposite blocks,

and when all the blocks are so connected, the structure so assembled will form a continuous coil of a single passage with two open ends, one for inlet and the other for outlet connection. This is all clearly -shown in the drawing-Figures 2, 3 and 4 The blocks may beplaced vertically instead of inclined, but if this is done, the tubes will not be parallel with the axis of the coil and it might be difficult to insert a cleaning tool into the tube, as it would be sprung out of line a distance equal to the spacing between tube centers. For this reason, I prefer the.

the present invention, it is to be understood that vvarious modifications and changes may be made without departing from the spirit of the invention and the invention includes all -other end and a plug in the end of the block screw-threaded into the bore.

2. A heating coil for cracking hydrocarbons, comprising a plurality of layers of tubes, diagonally arranged blocks for connecting the tubes of a layer each to the tubes of another layer at both ends, each block having a bore extending from one end nearly to the other end of the block, removable means for closing the open end of said bore and each block having screw threaded holes therein opposite the ends of each tube to permit a rod to be inserted in each tube for cleaning it out.

3. A heating coil for cracking hydrocarbons comprising a plurality of layers of tubes, diagonally arranged blocks for connecting the tubes of a layer each to the tubes of another layer at both ends, each block hav-l ing a screw-threaded bore extending from one end to near the other end, removable means for closing the open end of said bore and screw-threaded holes for the insertion of the tubes and additional screw-threaded holes opposite each tube with screw threaded lll plugs for insertion into the holes opposite the tubes.

4. A heating coil for cracking hydrocarbons com rising a plurality o layers of tubes, bloclts at each end of the tubes for connecting the tubes of a layer each to the tubes of another layer, the blocks at either ends of the tubes being diagonall arranged but parallel to each other, the tu es being so connected to the blocks that they form a coil having a single continuous assagev therethrough, each block having a ore extending from one end to nearly the other end of the block, the bores being approximately of the same diameter as the tubes, and a lu inserted inthe end of the bore of eac b ock, the tubes being arranged one above the other and clamps extending across the la ers an embracing the tubes at points subjected to the greatest heat to prevent the sagging of the tubes.

5. A heating coil for cracking hydrocarbons comprising a plurality of layers of tubes,

Adiagonally arranged blocks for connecting the tube ends of a layer each to the tube ends of another layer so that the tubes and blocks form a coil having a continuous singlepassage therethrough, each block havin a bore extending from one end to near the ot er end means toA close the' open end of the blocks and means detachably secured to the tubes to maintain them in s aced relation.

6. A heating coil for crackin hydrocarbons comprising a plurality o layers of tubes, -a plurality f blocks connecting the tube ends of a layer each to the tube ends of another layer so that the tubes and blocks form a coi having a continuous 'single assage therethrough, each block having a r'e extendin from one end to near the other end and a p ug in the end ofthe block screwthreaded into the bore.

7. A heating coil for cracking hydrocarbons comprislng .a plurality o layers 0f tubes, a plurality of blocks for connecting the tube of a layer' each to the tubes of another layer at both ends, each block having a bore extending from one end nearly to the other end of the block, removable means for closing the open end of said bore and each block having screw-threaded holes therein opposite the ends of each tube to permit a rod to be inserted in each tube for cleaning it out.

In testimony whereof Iaiix my si ature. JOHN C. BL CK. 

